Interrupted thread mount primarily for attaching a noise suppressor or other auxiliary device to a firearm

An apparatus for attaching an accessory to a firearm barrel having a longitudinal bore and a muzzle end, said apparatus comprising:

• a first adapter piece having a bore and configured for attachment to the muzzle end of the barrel with said bores substantially coaxially aligned and having a portion presenting a threaded connection with a circumference and an axial length;
• a second adapter piece configured for attachment to the accessory and having a portion presenting a threaded connection with a circumference and an axial length;
• wherein the threaded connection portions of the first and second adapter pieces are configured for threaded interconnection with one another, each portion including a plurality of circumferentially spaced, axially aligned segments of threads and thread interruptions, an interruption of the first piece corresponding in size and position to a threaded portion of the second piece and a threaded portion of the first piece corresponding in size and location to that of an interruption of the second piece,
• such that the threaded connection of the first and second adapter pieces may be axially slid together when corresponding interruptions and threaded portions are aligned and then turned no more than one half revolution to fully engage threads along the axial length thereof, said segments of threads and thread interruptions having unequal circumferential length such that there is a singular available orientation of the first and second adapter pieces to allow axial sliding engagement.